Method and apparatus for drying and separating sugars and other granular or comminuted materials



June 6, 1933. J NEUMAN ET AL 1,912,910

METHOD AND APPARATUS FOR DRYING AND SEPARATING SUGARS AND OTHER GRANULAR OR COMMINUTED MATERIALS Filed May 8, 1930 5 Sheets-Sheet 1 INVENTORS ATTORN Y June 1933- J. J. NEUMAN ET AL 1.9 29

METHOD AND APPARATUS FOR DRYING AND SEPARATING SUGARS AND OTHER GRANULAR OR COMMINUTED MATERIALS Filed May 8, 1930 3 Sheets-Sheet 2 INVENTORS J. I 11 672772471 0* ATTORNEY June 6, 1933. J J. NEUMAN r AL 1,912,910

METHOD AND APPARATUS FOR DRYING AND SEPARATING sUGARs AND OTHER GRANULAR OR COMMINUTED MATERIALS Filed May 8, 1930 3 Sheets-Sheet 3 INVENTORS fffi'zzmand I BY c ATTORNE Patented June 6, 1933 UNITED. STATES PATENT OFFICE.

JACOB J'- NEUMAN AND HARRY G. NEUMAN, OF NEW YORK, N. Y.

METHOD AND APPARATUS FOR DRYING AND SEPARATING SUGABS AND OTHER V GBANULAR OR COMMINUTED MATERIALS Application ama- May a, 1930. Serial No. 450,868.

This invention relates to a method and apparatus for drying and separating sugars and other granular or comminuted materials.

In recent years there has been an increasing demand for sugars having brlght, glossy crystals. With drying methodspand apparatus for handling sugars now in general .use, the crystal becomes scratched or broken and its surface lustre is completely lost. It is the primary object and purpose of our present invention to provide a new method of drying sugars which eliminates these objections and produces a sugar crystal having a high gloss or lustre.

Our improved method also contemplates, in one embodiment thereof, the grading or separation of the sugar grains or crystals according to the different sizes and weights thereof.

The method which constltutes the essen-- tial features of the present disclosure is pri marily characterized by the feeding of the wet sugar into a stream of heated air to the influence of which the sugar crystals are subjected for a sufiicient length of tlme to fully evaporate all moisture whereby thecrvstals are thoroughly dried, such air sti'eam also serving as a buffer or cushion between the individual crystals and the walls of the air duct or conduit so as to minimize breaking of the individual crystals or scratching of the surfaces thereof.

It is also an object of the invention to provide in combination with the receiving chamber for the dried sugar crystals, a simply constructed and reliably operating electrically actuated discharge gate or valve automatically controlled by the cumulative pressure influence of the sugar delivered to said chamber for moving said gate or valve to its open position to periodically discharge the dry sugar from said chamber.

With the above and other objects in view, the invention consists in the improved method and apparatus for drying and separating sugars or other granular materials, as will be hereinafter more fully described, illus- 50 trated in the accompanying drawings, and

tion, for drying and separating sugar crystals in accordance with my new method;

Fig. 2 is a similar view showing an alternative form of apparatus;

Fig. 3 is an elevation of the pressure operated mercury switch for controlling the operation of the sugar discharge gate or valve, a part of the switch housing being broken away and the mercury tube shown in section, and

Fig. 4 is a sectional view taken substantially on the line 44 of Fig. 3.

Referring in detail to the drawings, and more particularly to Fig. 1 thereof, 5 designates a suitable type of blower, and 6 a horizontally disposed conduit or duct extending from the outlet side of the blower. This duct is suitably joined with the lower end of the vertically disposed conduit 7 and adjacent the point of connection of these two conduits, a suitable type of heater conventionally indicated at 8 is interposed in the conduit 6.

Adjacent its upper end a horizontally disposed casing 9 is connected with the conduit 7 and houses a conveyor 10 which conveys the wet sugar from a supply hopper 11 and discharges the same into the conduit 7. Above the casing 9, the conduit 7 is laterally extended and connected with the upper end of the return conduit 12, the lower end of which is connected with the intake of the blower 5. In this return conduit a suitable form of condenser conventionally indicated at 13 is interposed.

Between the blower 5 and the heater 8 one end of a branch conduit 14 is connected with the conduit 6 and is provided with a receiving hopper 15 beneath the lower open end of the conduit 7. Beyond the hopper 15, the conduit 14: is vertically extended upwardly and opens into an expansion chamber 16. The upwardly extending outlet 17 of this chamber opens into a second expansion chamber 18 and the outlet 19 of the .atter chamber opens into a third expansion chamber 20. It will be noted that these expansion chambers 16, 18 and 20 successively increase in size or dimensions. The lower end of each chamber is provided with a valved outlet as indicated at21, 22 and 23 respectively, for the sugars collecting therein. The upper end of the expansion chamber 20 is connected by the conduit 24 with the upper end of the return conduit 12, preferably at the juncture between said conduit and the upper end of the conduit 7.

Suitable dampers or control valves 25 and 26 are provided for controlling and regulating the air pressures within the conduits 7 and 14.

In the operation of the above apparatus, the wet sugar is supplied to the hopper 11 and discharged into conduit 7 by the conveyor 10. The air from the blower 5 having been heated prior to its entrance into the lower end of the conduit 7 flows upwardly through said conduit under high pressure, and intercepting the wet sugar,

retards the downward gravity fall of the sugar through the conduit. The degree of this retardation and the rapidity of the gravity descent of the sugar through the conduit may be properly controlled and regulated by adjustment of the damper or valve 25. As the downward movement of the sugar progressively continues through the conduit 7 it is subjected to a gradually in-. creasing degree of heat in the air stream enterin the lower end of said conduit so that all moisture is completely evaporated and carried off by the heated air and when the sugar finally enters the hopper 15 it is in a thoroughly dry condition. A sugar seal is maintained in the hoppers 11 and. 15 to prevent air leakage from the conduits. Heated air finally leaves the upper end of the conduit 7 and enters the condenser 13 from the return conduit 12 where the moisture or vapor is condensed and the desaturated air then returned to the blower 5.

A further important feature of the invention is to cool the dry sugar and separate or segregate sugar grains or crystals of different sizes from each other. This is accomplished by properly adjusting the valve or damper 26 so that a predetermined portion of the volume of air delivered from the blower 5 is supplied to conduit 14 before the air reaches the heater 8. This unheated air picks up and conveys the dry sugar falling from hopper 15 through the conduit 14 and discharges the same from the upper end of this conduit into the first expansion chamber 16. Here the air pressure is reduced to such a degree that the sugar grains or crystals of the greatest specific gravity, separate and are precipitated into the lower end of the chamber for discharge through its outlet 21. The air and the remaining sugar then passes upwardly through the chamber outlet 17 and is discharged into the second expansion chamber 18 in which a further reduction 'in air pressure takes place so thatthe sugar grains or crystals of the intermediate size and specific gravity, separate and are precipitated in this chamber to be discharged through the outlet 22. The finest and lightest sugar grains or crystals are then delivered through the outlet 19 of the uppermost and largest expansion chamber 20 where a final reduction in air pressure takes place and these finer sugar crystals are precipitated for discharge through the chamber outlet 23. In this conveyance of the sugar crystals and the successive separation of the same into crystals of various different sizes, the sugar is of course, cooled and individual crystals acquire a high polish or lustre. The air finally passes off from the upper chamber 20, enters conduit 24 and is returned through conduit 12 with the heated air from the conduit 7 to the blower 5. i

From the above description, it will be seen that the heated air for the purpose of drying and the cold air for the purpose of cooling and separating the sugar crystals functions in a closed circulatory system so that my new method may be practiced with the use of apparatus of mechanically simple construction which may be continuously operated with a minimum consumption of power at very low maintenance cost. It will be noted that the forcible impact of the sugar crystals with metal walls or other surfaces is avoided, the individual sugar crystals being at all times suspended in the air streams and toa large extent protected and cushioned by the air against contact with the conduit walls. In this manner, we have succeeded in practically eliminating breakage of the individual crystals or scratching of their glossy facets or surfaces.

In Fig. 2 of the drawings, we have illustrated another form of apparatus for drying the sugar crystals in which the vertical conduit 7 is connected with the heater 8 and the blower 5 in the same manner as heretofore described and the wet sugar is fed into the path of the heated air stream flowing upwardly through said conduit at a point substantially midway between its ends by the conveyor 10'. In this case, the air pressure developed by the blower 5' is sufiiciently great to carry the wet sugar in suspension upwardly through the conduit 7 and discharge the same from the laterally extended upper end of the conduit into the receiving 0 amber 28. During this conveyance of the sugar by the heated air stream, the moisture is substantially entirely evaporated so that the sugar crystals are discharged into the chamber 28 and in a substantially dry condition. However, we referably make this chamber of cylin rical form so as to obtain a whirling or cyclone separating effect. The sugar finally settles in this receiving chamber while the air is exhausted therefrom through the filter bag shown at 29.

The sugar receiving chamber 28 is provided at its lower end and at the opposite end thereof from the connection with the;

conduit 7 with a downwardly inclined discharge outlet 30 which is normally closed by means of a vertically movable gate valve 31 connected with the core of the solenoid 32 to be operated to its open position when the solenoid is energized.

For the purpose of periodically and automatically closing the current supply circuit for the solenoid 32, we provide the chamber or container 28 forthe dry sugar with a bypass shown at 33 communicating at its lower end with the inner end of the discharge outlet 30, and one wall of said bypass having an opening therein affording communication between the upper end of the bypass and the chamber 28. This opening is normally closed by the .pivoted gate 34 and is operatively connected by means of the rod or link 35 with the movable element of a normally open switch generally I indicated at 36.

the operation of the apparatus. Upon reference to Figs. 3 and 4, it will be seen that the several movable switch parts are enclosed within a suitable casing or housing 38. In one side wall of this housing a shaft 39 is rotatably mounted and has an arm 40 fixed to one of its ends externally of the switch housing to which the rod or link 35 is pivotally connected. To the inner end of said shaft, a suitable clamping device indicated at 41 for the mercury tube 42 is attached. Terminals 43 are sealed in the opposite ends of this tube and are connected by the conductors 44 and 45 respectively, with one of the poles of the switch 37 and one of the windings of the solenoid 37. The mercury containing tube 42 is held in a normal position by means of a coil spring 46 which also yieldingly resists movement of the pivoted gate from its normal closed position. As shown in Fig. 3 of the drawings, the tube 42 in its normal biased position maintains the mercury in the tube at such level that it is out of contact with one of the terminals 43. As the dry sugar gradually accumulates in the chamber or container 28, the. pressure thereof against the inner side of the gate 34 gradually increases. When this pressure becomes sufiicie'ntly great to overcome .the contractile pull of the spring 36, the gate 34 will bemoved to the open qlositi'on shown in dotted lines in Fig. 2 so t at the dry sugar from the upper end of the chamber 28 will enter the bypass 33. In this opening movement of the gate, through the rod connection 35. therewith, the mercury tube 42 is oscillated so that the fluid mercury therein is caused to engage each of the terminals 43, thereby closing the circuit and energizing the solenoid 32, whereby tion. A portion of the contents of the chamber or container 28 is thus discharged through the outlet 30 upon a suitable conveyor indicated at 47 which carries the sugar to a desired point for further processing. Upon decrease of the pressure resistance of the sugar against the pivoted gate 34 to a point below'the strength of the spring 46, the said spring will act to return the mercury tube and the gate 34 to their normal positions, thus breaking the circuit and deenergizing solenoid 32 so that the gate valve 31 moves to its closed position and thus cuts oil further discharge of sugar from the outlet 30.

A similar periodically operating automatic discharge control means may also be employed if desired, in connection with the discharge outlets of the several separating or expansion chambers 16, 18 and 20 shown in Fig. 1 of the drawings.

From the foregoing description considered in connection with the accompanying drawings, the several novel features of our improved method of drying and selectively segregating or separating the sugar crystals of different sizes will be clearly and fully understood.

Also as herein disclosed, it will be appreciated that this method may be practically carried out by means of simple and inexpensive apparatus which will be highly reliable in the performance of its functions and require little care or attention in order to maintain the same at its highest operating efiiciency. It will however, be understood that the illustrated embodiments of the apparatus are more or less suggestive, and that insofar as the essentially novel features of such apparatus-and of the new method are concerned, the same might be exemplified in various other structural forms. Therefore, that we reserve the privilege of adopting all such legitimate changes in the form, conit is to be understood struction and relative arrangement of the various parts of the apparatus as may be fairly considered within the spirit and scope of the invention as claimed.

We claim:

1. In the art of drying granular materials, the method which consists in ,maintaining a continuous flow of air through a closed circuit, feeding granular material into the air stream during its flow through one part of said circuit whereby gravitational movement of the material is counteracted and said material maintained in suspension to eflect evaporation of its moisture content, diverting a part of the air from said closed circuit, and discharging the dried material into said diverted current of air to be conveyed by the latter to a receiving chamber.

2. In the art of drying granular materials, maintaining a continuous flow of air under predetermined pressure through a closed circuit, heating the air after development of pressure, feeding wet granular material into the heated air stream during its flow through one part of said circuit to cause said heated air to partially counteract and retard the gravitational movement of the material to maintain the latter in suspension for the necessary time to effect the evaporation of all moisture therein, diverting a part of the air after development of pressure and before heating from said closed circuit, and discharging the dried material into said diverted current of unheated air to be cooled thereby and conveyed to a receiving chamber.

3. In handling granular materials, the method which consists in maintaining a flow of heated air under predetermined pressure through a conduit, delivering wet granular material having granules of relatively different specific gravities into the path of flow of the heated air whereby the material is subjected to the pressure influence of the heated air to maintain the material in suspension and efi'ect evaporation of the moisture content thereof, maintaining a flow of unheated air under pressure through another conduit and discharging the dried material fromthe first conduit into said other conduitto be conveyed and cooled by the air therein, and progressively separating the granules of different specific gravities from the mass of the material during its conveyance through the latter conduit.

4. In drying and separating sugar into the granular or different specific gravities,

the method which consists in maintaining a' flow of air under pressure through a closed circuit and heating such air subsequent to the development of pressure, feeding the wet granular material into the path of flow of the heated air to subject the same to the pressure influence of the air and maintain the material in suspension in said circuit for the required length of time to effect the evaporation of its moisture content, diverting a part of the air from saidcircuit prior to heating thereof and maintaining a separate current flow of air under pressure and returning said diverted air to the return side of the circuit path of flow of the heated air, discharging the dried material from the heated air circuit into the diverted current of unheated air, and progressively separating the granules of different specific gravities from the mass of material during its conveyance by the unheated air current and prior to the return of such unheated air to the circuit path of flow of the heated air.

5. Apparatus for handling materials composed of granules of diflerent specific gravities comprising vertically disposed conduit means forming a closed circuit and means for producing a continuous circulation of air under pressure therethrough, means in terposed in said conduit means for heating the air, means for feeding wet granular material into one branch of the conduit in spaced relation to said pressure producing means and subjecting the same to the pressure influence of the heated air to retard gravity movement of the material and effect evaporation of its moisture content, a branch conduit connected with said conduit means to receive a part of the air therefrom prior to heating the same, the other end of said branch conduit being connected with said conduit means to return the diverted air thereto, means for receiving the dried material from the main conduit and delivering the same into said branch conduit to be cooled and conveyed by the air flowing therethrough, and a plurality of spaced expansion chambers in said branch conduit for progressively separating the granules'of different specific gravities from the conveyed material prior to the return of the diverted air to the main conduit means.

6. Apparatus for handling granular materials comprising vertically disposed conduit means forming a closed circuit and means for producing a continuous circulation of air under pressure therethrough, means interposed in said circuit means for heating the air, means for feeding wet granular material into one branch of the conduit in spaced relation to said pressure proering the same into said branch conduit to be cooled and conveyed by the air flowing the'rethrough.

In testimony that we claim the foregoing 5 as our invention, we have signed our names hereto.

JACOB J. N'EUMAN. HARRY G. NEUMAN. 

